Neuro Flashcards

Question

What are the functions of astrocytes

Answer 1

1. Form glial membrane (external limiting membrane) 2. Component of blood-brain barrier a. Control K+ b. Modulate vascular tone in the brain, controlling cerebral blood flow. 3. Remove a. K+ from extracellular fluid at nodes of Ranvier during action potentials. b. Neurotransmitters from synaptic clefts (Prevents glutamate excitotoxicity.) 4. Communicate through gliotransmitters (D-serine, glutamate, ATP) in response to adjacent synaptic activity. 5. Produce neurotrophic factors. 6. Produce scar tissue in response to CNS injury

Answer 2

Satellite glial cells are the principal glial cells found in the peripheral nervous system, specifically in sensory, sympathetic, and parasympathetic ganglia. They compose the thin cellular sheaths that surround the individual neurons in these ganglia. SGCs have been found to play a variety of roles, including control over the microenvironment of sympathetic ganglia. They are thought to have a similar role to astrocytes in the central nervous system (CNS). They supply nutrients to the surrounding neurons and also have some structural function. Satellite cells also act as protective, cushioning cells. Additionally, they express a variety of receptors that allow for a range of interactions with neuroactive chemicals.

Answer 3

Vertebrae - C1-C7 * T1-T12 L1-L5 S Nerves, C1-C7, C8*. So the spinal nerves exit in the intervertebral foramen above the vertebraes. So C8 vertebrae does not exist but the nerve does. All the other nerves exit in a foramen below so T1-T12, L1-L5, S1-S5 The conus medullaris is around L1

Answer 4

A unipolar primary sensory neuron synapses with a secondary sensory neuron in the dorsal horn. The tract neuron crosses the midline (decussation) and travels up to the brain via the anterolateral pathway aka spinothalamic and synapses at the thalamus where an interneuron that takes the signal to the primary somatosensory cortex A major sensory tract fro the spinal cord to the cortex, crosses in the spinal cord, so the representation is in the opposite brain.

Answer 5

The brain stem - features long pathways, and cranial nerves instead of spinal nerves. They are important for functions the head can do like facial expression, ingestion, respiration --keep in mind the flexure when taking locations--- from rostral to caudal - midbrain, pons, medulla oblongata Midbrain: cerebral peduncle * Cranial, only 3 and 4 - visual reflexes, visual motor control - **has dopamine projections to corticol areas significant for movement and "reward" Pons - balloon aka "big bridge to cerebellum" Cranial nerves - 5,6,7,8 Function - balance, sound localization, eye movement coordination Medulla -pyramid Cranial nerves - 9,10,11,12 Function: -regulation of body homeostasis/heart rate, respiration, vasomotor tone, gastric secretions -vomiting, coughing, sneezing, swallowing, gagging Damage to medulla is death

Answer 6

Major component: reticular formation--- Nuclei and neuronal circuits • Net-like appearance • Through the core of the brainstem. • Include projections to the cortex or spinal cord. RAS - beings in the reticular formation Rostral projections from the pons and midbrain (pontomesencephalic) • Projection controls attention, arousal, sleep and wakefulness. • Includes several neurotransmitters systems

Answer 7

Corticospinal tract: Major motor pathway from the cortex to the spinal cord. Upper motor neuron crosses in the medulla to control contralateral muscles. Projects to the spinal cord from the primary motor cortex as all do, - crosses at the medulla "pyramid decussation - travels through the lateral corticospinal tract - synapses in the anterior horn with the lower motor neuron which synapses on skeletal muscle

Answer 8

Blood-CSF - choroid plexus which produces CSF and is found in all the major ventricles - blood vessels entering the choroid plexus 1. Endothelial wall of the choroidal capillaries: No barrier-- are fenestrated. 2. Scattered pial cells. 3. Choroidal epithelial creates a blood-CSF barrier by tight junctions – active transport, ion exchange mechanisms to determine flow of molecules (e.g., Na+, K+, Cl-, Mg++, folates) Blood-brain barrier -blood vessels in subarachnoid space meeting brain tissue -is formed by tight junctions between the brain capillary endothelial cell. Astrocyte foot processes surround the capillary but are not part of the barrier. They can control blood flow Controls ionic environment--neurotransmission Protects brain from toxins Prevents drugs from entering brain Contains transporters for some critical molecules (glucose and proteins) The blood-brain barrier may be disrupted by infections, tumors or trauma, causing “vasogenic edema”

Answer 9

1. Arterial blood crosses the choroid epithelium 2. Lateral ventricles > 3. Interventricular foramen of Monroe > 4. 3rd ventricles > 5. Cerebral Aqueduct > 6. 4th ventricle > 7. Foramen of Magendie (1 medial) and Luschka (2 lateral) > 8. Subarachnoid space around brain and spinal cord 9. Arachnoid granulations > venous sinuses END

Answer 10

.Lumbar puncture L3-L4 in adults L4-L5 in children. Contraindicated if there is HIGH Intracranial pressure: you could create a vacuum causing brain herniation CSF pressure: normal is <20 cm H2O in lying position 1. Obtaining samples of CSF important for identifying: - subarachnoid hemorrhage (detect blood) - infections ex. meningitis - Guillain Barre - an ascending weakness/paralysis commonly caused by GN Campylobacter Jejuni in which the body's immune system attacks part of the peripheral nervous system - MS 2. Introduce drugs

Answer 11

Brain: ---pachymeninges------- Dura: 2 layers -periosteal -meningeal - ---leptomeninges------- - Arachnoid - many arachnoid trabeculae and cisterns - Pia Spinal cord: - 1 layer of dura mater - Arachnoid- fewer trabeculae and 1 cistern - Pia - forms denticulate ligaments (secures to arachnoid), filum terminale internum attaches to arachnoid, externum attaches to coccyx.)

Answer 12

``` Falx cerebri - in between cerebral hemispheres (in longitudinal fissure). ``` Falx cerebelli - in between two hemispheres of cerebellum. Tentorium cerebelli - in between the posterior cerebral hemispheres and the cerebellum. Wraps around the brain stem, forming a roof Diaphragm sellae - circular fold beneath the brain that covers the sella turcica. Herniation: 1- Temporal transtentorial herniation aka uncal tentorial notch: the midbrain reticular formation goes right through the notch which is a tight space. If there is increased pressure in the supratentorial space, the brain can herniate right there, go into a coma because RAS is impinged. Tumor in temporal lobe can cause this. 2. Subfalcine aka Subdural- cingulate gyrus herniates below the falx cerebri - the most common form and does not necessarily mean severe symptoms, present as headache but can progress to contralateral leg weakness. 3. Central herniation or downward transtentorial: the diencephalon (thalamus and hypothalamus) and medial parts of both temporal lobes are forces through a notch in the tentorioum cerebelli. 4. Cerebellar tonsillar - is a type of cerebral herniation characterised by the inferior descent of the cerebellar tonsils below the foramen magnum. (seen in chiari I malformation

Answer 13

Epidural space: Potential space between the dura and the skull * note in the spinal cord this is a real space filled with epidural fat. - the middle meningeal artery lies on the dura mater so tearing can cause bleeding into the epidural space. Subdural space: Potential space between the dura and arachnoid - subdural hematoma: usually venous blood (bridging veins) Subarachnoid space: Real space where the major arteries of the veins are found

Answer 14

Electromyographic changes: fibrillations, positive sharp waves, fasciculations. These are measures of denervation. Electromyography is an investigatory tool to assess the source muscle weakness 1. Needle electrodes inserted into muscle 2. Study muscle at rest (normal: no activity) 3. During a contraction Fibrillation: only detected with EMG. Short-duration, spontaneous biphasic or triphasic potentials produced by single muscle fibers. These are indicative of a denervated muscle. These are thought to represent an unstable muscle fiber cell membrane. They both occur in peripheral nerve injuries, axonal neuropathies, motor neuron disorders and some myopathies. Fasciculations: Larger potentials caused by spontaneous activity in a motor unit or several motor units. Caused by lower motor neuron lesions, particularly in anterior horn cell disease such as ALS. Large potentials are suggestive of denervation and reinnervation.

Answer 15

.The polio virus attacks ventral horn motor neurons, causing LMN syndrome Recovery and stable period is due to sprouting by neighboring motor neurons So patient has period of years during which she was neurologically stable. (usually ~ 15 years) followed by progressive weakness in the same muscles originally affected. Post-polio period occurs years later because those new sprouts cannot be sustained.

Answer 16

The muscles that are innervated by motor neurons 1. Weakness or paralysis 2. Atrophy - Muscle atrophy: Without motor neuron innervation, muscles cannot contract, so lose mass. They also lose trophic support from the motor neurons. 3. Hyporeflexia or areflexia 4. Decreased tone (resistance to passive movement) “flaccid paresis/paralysis” 5. Fibrillations, positive sharp waves or fasciculations, measured by EMG

Answer 17

Cell bodies in CNS (Ventral horn or brainstem nuclei) Axons in the PNS in ventral root, spinal nerve, peripheral nerve, or cranial nerve 1. Peripheral nerve, spinal nerve, or cranial nerve lesions 2. Cauda equina lesions 3. Strokes or tumors affecting alpha motor neurons in ventral horn or brainstem 4. Polio (viral infection of α-motor neurons) 5. Amyotrophic lateral sclerosis ( “ALS” or “motor neuron disease” that also affects upper motor neurons) 6. Guillain-Barré (demyelinating disease) 7. Werdnig-Hoffman disease (degeneration of anterior horn)

Answer 18

C2-back of head C5-shoulder, lateral arm C6-digits 1-2, lateral forearm C7-digit 3 T10-umbilicus (belly butten) L4-knee, and medial lower leg (down on ALL 4's) L5-dorsal foot, big toe S1-lateral foot, small toe, So1e

Answer 19

Anterior spinal artery (1) located in the ventral median fissure - Supplies anterior 2/3 of spinal cord Posterior spinal artery (2) located in the posterolateral sulci Supplies posterior 1/3 of spinal cord Vasocorona: a series of branches from the anterior and posterior spinal arteries that form a crown (“corona”) around the cord. Anterior and posterior radicular arteries arise from segmental arteries at each spinal level to serve their respective roots and ganglia. • The anterior and posterior spinal medullary arteries arise at intermittent levels to augment the blood supply. • The great Artery of Adamkiewicz is unusually large anterior radicular artery arising on the left from T9-L1. It supplies the majority of the lumbar and sacral SC. Great radicular artery of adamkiewicz is so important that it is thought to supply the whole bottom of the spinal cord and blockage presents as a lower spinal cord injury

Answer 20

T4-T9 watershed area ``` • Fracture dislocations of vertebra can interfere with blood supply. • Arterial disease can obstruct great radicular artery. • Occlusion of aorta during surgery can produce ischemic damage to blood supply. ``` Its a region between the endpoints of the thoracic radicular artery & great radicular artery of adamkiewicz Drop in blood pressure, can lead to this watershed region being necrotic.

Answer 21

C3-C5 Motor neurons to the Phrenic nerve controlling diaphragm. S3-S4 Onuf’s nucleus: Motor neurons innervating urethral and external anal sphincter which enable voluntary control of urination and defecation. S2-S4 Motor neurons to pelvic floor muscles. *very low spinal cord lesions (cauda equina) can produce bowel and bladder incontinence

Answer 22

An acoustic neuroma is a noncancerous growth that develops on the eighth cranial nerve. Also known as the vestibulocochlear nerve, it connects the inner ear with the brain and has two different parts. One part is involved in transmitting sound; the other helps send balance information from the inner ear to the brain.

Answer 23

1. Enough graded potentials activate voltage gated sodium channels (-50mV) 2. Sodium influxes, the neuron depolarizes significantly. 3. Then the sodium channels close and potassium channels open, hyperpolarizing until the voltage gated potassium channels close. 4. inactivated sodium channels are no longer inactive.

Answer 24

There is a process of endocytosis to remove membrane from the nerve terminal. Adaptor proteins connect clathrin to vesicular membrane forming clathrin coated pits. Clathrin assemble into coat, curving membrane. Dynamin ring comes and pinches off membrane. Coated vesicle is then moved away from terminal along the actin filament Hsc70/Auxillin - remove the clathrin. Can start storing NT again

Answer 25

The major excitatory neurotransmitter in the CNS • Contained in approximately 50% of all neurons, and virtually all excitatory neurons. • Post-synaptic receptor type: Metabotropic: May be excitatory or inhibitory, depending on the state of the neuron. • Ionotropic: NMDA (N-methyl-D-aspartate), kainate and AMPA. **All excitatory NMDA is both a voltage-gated and ligand-gated Ca2+ ion channel • The receptor is blocked by Mg2+ at resting membrane potential • Uses the AMPA receptor and influx of Na+ to depolarize the membrane to remove the Mg2+ block It is both a voltage-gated and ligand-gated Ca2+ ion channel • The receptor is blocked by Mg2+ at resting membrane potential • Uses the AMPA receptor and influx of Na+ to depolarize the membrane to remove the Mg2+ block NMDA activation in the presence of depolarization, enables Ca2+ to enter cell. • Increased intracellular [Ca2+ ] can activate calcium-dependent signaling cascades. • Intracellular signals can produce long-term synaptic changes that are important for • development of synapses • regulating neural circuits • learning and memory (Long-term potentiation; LTP) • Long-term changes include changes in dendritic spines and insertion of AMPA receptors: Increased responsiveness of post-synaptic neurons after repeated stimulation of neurons (e.g., in hippocampus).

Answer 26

Trauma and disease that impair ATP-generation can cause increased glutamate release or decreased glutamate reuptake. • Glutamate NMDA channels allow Ca2+ to leak into cells. • Increased Ca2+ causes increased water uptake and stimulation of intracellular enzymes that degrade proteins, lipids, and nucleic acids • Examples of conditions thought to be associated with glutamate toxicity: ALS, Alzheimer’s, tumors, oxygen deficiency, ischemia, trauma, repeated seizures.

Answer 27

Major inhibitory neurotransmitter of the CNS • Contained in about 30% of CNS neurons * Post-synaptic receptor type: * Ionotropic: GABAa receptor, GABA gated Cl-channel * Metabotropic: GABAb functionally linked to potassium or calcium ion channels

Answer 28

Mesolimbic pathway: -Reward pathway (addiction) - Schizophrenia - Depression Nigrostriatal Pathway: Control of movement -Parkinson’s disease Mesocortical pathway: Working memory Schizophrenia ADHD Involved in reward-motivated behavior and motor pathways CNS- Neurons originate in brainstem regions (ventral tegmental area and substanstia nigra) 46 Drugs that influence dopamine transmission: • Anti-psychotics (-) • Nicotine, cocaine, methamphetamine (+) • Amphetamines (Adderall) (+) • Methylphenidate (Ritalin) (+)

Answer 29

Main neurotransmitter in the PNS and ANS, but also has neuromodulator functions in CNS • PNS- Neuromuscular junctions • ANS- sympathetic (pre-) & parasympathetic (pre- & post- ganglionic) neurons • CNS- Neurons originate in the basal forebrain (*nucleus basalis) and the brainstem (*dorsolateral midbrain-pons) and have widespread connections to the cortex * Involved in arousal, attention, memory and motivation • Nucleus basalis degenerates in Alzheimer’s disease * Associated with memory loss, personality change and dementia Drugs that influence ACh transmission in the CNS: • Nicotine (on nictotinic receptors) (+) • Atropine (-) • Scopolamine (-)

Answer 30

So in the cervical vertebrae, because the corresponding nerve exits above the vertebrae, a C5-C6 herniated disc impinges on C6 nerve. In the lumbar its the same but for a different region. The interventricular foramen is large so the corresponding spinal nerve exits above the disc. So an L4-L5 herniation will not impinge onf the L4 nerve but rather the L5 as it is traveling in the cauda equina. Impinging the L5 nerve.

Answer 31

Paralysis: weakness so severe that a muscle cannot be contracted. • Paresis: weakness, or partial paralysis. • Plegia: severe weakness or paralysis. – e.g., Diplegia refers to bilateral lower limb weakness. Quadriplegia to all 4 limbs. – Hemiplegia refers to one side of the body weakness (arm and leg) • Palsy: imprecise term for either weakness or no movement.

Answer 32

.0/5 No contraction 1/5 Muscle flicker, no movement 2/5 Movement, but not against gravity 3/5 Movement against gravity, but not against resistance 4/5 Movement against some resistance 5/5 Normal ``` 0+ absent 1+ trace 2+ normal 3+ brisk 4+ non-sustained clonus 5+ sustained clonus 1-3 can look normal so always refer to opposite side for asymmetry or even with upper and lower ```

Answer 33

Stretch reflex - 1. Muscle stretch receptor excited (connected to Ia afferent) 2. Ia afferent makes an excitatory synapse onto quadriceps motor neurons, causing muscle contraction 3. Ia afferent also makes an excitatory synapse onto an inhibitory interneuron, which inhibits hamstring (flexor) motor neurons (L3,L4) Golgi tendon reflex Stimulus: Muscle tension Circuit: GTO > lb > lb inhibitory interneuron > motor neuron to homonymous muscle (also excites antagonist muscles) Flexor withdrawal - stimulated leg flexes to withdraw after cutaneous receptor activated > cutaneous afferent fiber from nociceptor alpha, < activates interneurons which inhibit the extensors and activate flexor in pained foot > for opposite foot the opposite happens, extensor activated, flexor inhibited to stand

Answer 34

L3-4 – patella (3,4 kick down the door) C5-6 – biceps C5-6 – brachioradialis (5,6 pick up sticks) C7-8– triceps (7-8 keep it straight) S1 – Achilles (1,2 buckle my shoe)

Answer 35

Proprioceptors: providing information about body position/movement. -Arranged in parallel with skeletal muscles fibers. • Intrafusal muscle fibers within a connective tissue capsule. • Attached to skeletal muscle fibers. Muscle spindle contains this lil capsule, which has efferent (gamma) and afferent nerves. It has two types of sensory nerves, group Ia which responds to rapid, dynamic stretch and group II which responds to sustained, tonic stretch Gamma motor neuron: γ-motor neurons are motor neurons that only innervate muscle spindle intrafusal fibers. • DO NOT cause skeletal muscle fibers to contract. • Increase the excitability of the muscle spindle. Normally both alpha- and gamma- motor neurons are CO-activated. • Gamma activity increases during skilled movements and motor learning. So stretch is going to have a greater response with gamma neuron activity and also picks up slack if muscles are contracted Describe the functions of the corticospinal, corticobulbar and reticulospinal tract pathways.

Answer 36

Corticospinal tract: The corticospinal tract is the primary pathway for goal-directed movements. • Only descending pathway to project directly to α-motor neurons of distal muscles. • It is the only pathway that generates fine movements of the fingers. The corticospinal tract originates in the primary motor cortex as well as the premotor and somatosensory cortex. *Large Betz Cells in motor cortex (layer 5) project directly to motor neurons Reticulospinal tracts project mainly ipsilaterally (some bilateral) to medial α-motor neurons throughout the length of the spinal cord. They contribute to posture and gait-related movements. Generate feedforward preparatory muscle activation. •Contribute to muscle tone. Corticobulbar The corticobulbar tract is a descending pathway responsible for innervating several cranial nerves, and runs in paralell with the corticospinal tract Origin - Motor cortex (precentral gyrus and anterior part of the paracentral lobule) Course / Path - The corticobulbar tracts leave the internal capsule and enter the basilar part of the pons as numerous bundles [1] The fibres leave the cerebral crus adjacent to the corticospinal tract.[1] The fibres can take several paths and have several different terminations: i) Termine directly on alpha motor neurones or interneurones innervating alpha motorneurons in the brainstem. These control somatic motor acitivity in the head e.g. muscles that control mastication, expression and eye movement. ii) Axons that innervate motor nerve cranial nuclei can decussate (cross) before they terminate, resulting in them innervating contralateral muscles. As some decussate and some descend ipsilaterally, it results in bilateral descending control. [2] iii) Directly innervate cranial nerves or through interneurones I.E. via the corticospinal tract. [2] Function - Innervates muscles of the face, tongue, jaw, and pharynx, via the cranial nerves.[3] - The corticobulbar tract directly innervates the nuclei for cranial nerves: V - Trigeminal- muscles for mastication VII- Facial- muscles of the face XI- Accessory- sternocleidomastoid and trapezius XII- Hypoglossal- muscles of the tongue [4] - Cranial nerves motor regions of X (vagus nerve) in the nucleus ambiguus.[4]

Answer 37

Lesions above the spinal cord produce contralateral deficits. Lesions of the spinal cord produce symptoms on the same side of the lesion Deficits are always below the level of the lesion ________________________________ Corticospinal Tract: Major deficits with CST lesions: •Voluntary motor weakness (distal > proximal) on one side of the body. •Babinski sign ______________________________ Trauma to lateral primary motor cortex 1. Weakness in right arm and low face 2. UMN (lower face, entire arm). 3. Pathways are CBT and CST aka. Contralateral Unilateral face and hand hemiparesis. ________________________________ Trauma to internal capsule Pure motor hemiparesis with lesion in internal capsule- starting with the lower face. _________________________________ Trauma to motor cortex (contralateral) •A lesion affecting the ipsilateral spinal cord—UMN signs •Peripheral nerve--LMN signs

Answer 38

Cutaneous (AlphaBeta) -Meissner corpuscle: surface, motion in dermis -Merkel cell: detects edges, indentations, slowly adapting - Ruffini corpuscle - skin stretch, aligned parallel with stretch lines - Pacinian corpuscle: deep and with onion like layers, vibration Proprioception: (1a, II) - the largest, most myelin, fastest - muscle spindle - GTO Temperature (Alphadelta, C) Pain (Alphadelta, C)

Answer 39

The interaction of nociceptors with the “inflammatory soup” of substances to decrease threshold of activation for nociceptors Prostaglandins: •Increase response of nociceptive fibers. These nociceptors release substance P which causes vasodilation but also mast cell degranulation releasing histamine as a positive feedback cycle since histamine also activates nociceptors. Nonsteroidal anti-inflammatory drugs (NSAIDs) (e.g. aspirin and ibuprofen): •Inhibit cyclooxygenase (COX) to prevent synthesis of prostaglandins

Answer 40

An immediate, activity dependent increase in the excitability of neurons in the dorsal horn of the spinal cord following high levels of activity in the nociceptive afferents to increase pain sensitivity. Mechanisms of central sensitization 1. Transcription independent (windup) lasts only during stimulation = acute. 2. Transcription dependent (allodynia) outlast stimulus for hours and can be mediated by COX = chronic. • Development of or increase in spontaneous activity • Reduction in threshold for activation by peripheral stimuli • Expansion of receptive field size (conversion of nociceptive-specific neurons to wide dynamic neurons that now respond to both innocuous and noxious stimuli) -the glutamate channel is open, with repeated stimuli you unblock the NMDA receptor which initiaties a signal cascade. With repeated stimulation, with alot of NT, gene expression changes which permanently changes the neuron

Answer 41

Lateral vestibulospinal (balance): projects to the entire spinal cord. It projects **ipsilaterally to medial LMNs to proximal muscles. Especially facilitates extensor muscles in response to deviations from stable balance and upright balance. ``` Medial vestibulospinal (positioning of head and neck): projects on to cervical.Projects BILAterally to control head position in response to acceleration "vestibulocervical reflex ``` important in reflex excitability

Answer 42

Originates in the superior colliculus and crosses in the MIDBRAIN (not just the one of the only ones to cross in the midbrain but out of the brain stem pathways, the only one to cross at all! ) (tecto and rubro) Is in the medial motor system. Generates orienting movements of the head to visual or auditory stimuli. It also helps to coordinate the eyes and head.

Answer 43

Originates in the red nucleus of the midbrain. Crosses in the midbrain Travels next to LCST in the spinal cord Only extends to the *cervical spinal cord Facilitates FLEXOR muscles>extensors * this is important because its where a decerebrate - lesion below the midbrain - cause ALL LIMBS to extend vs decorticate which has flexion of the arms. ONLY pathway that travels and projects lateral! Lateral: only the LCST and rubrospinal

Answer 44

1. anterior corticospinal tract 2. Reticulospinal tract 3. Lateral vestibulospinal tract 4. Medial vestibulospinal tract 5. Corticobulbar

Answer 45

1. anterior corticospinal tract 2. Reticulospinal tract 3. Medial vestibulospinal tract (cervical only) 4. Most of corticobulbar

Answer 46

Diagnosis: upward gaze paresis Limb ataxia MRI showed a pineal cyst compressing nerves responsible for eye movement and motor movement. In most cases, a pineal cyst does not cause signs or symptoms. The majority of pineal cysts are small (roughly 80% are less than 10 mm in diameter) and asymptomatic. Symptomatic lesions are often larger (but not always), and occur most often in women in their second decade of life. Larger cysts (with a diameter >15 mm) may lead to various neurologic symptoms. Symptoms may be due to the cyst's proximity to other structures in the brain, or hydrocephalus from compression of the cerebral aqueduct (a channel connecting the 3rd and 4th ventricles of the brain).[5] When a pineal cyst does cause symptoms, they may include headaches (the most common symptom), hydrocephalus, disturbances in vision, and Parinaud syndrome. Although rare, people with symptomatic pineal cysts may have other symptoms such as difficulty moving (ataxia), mental and emotional disturbances, vertigo, seizures, sleep (circadian rhythm) troubles, vomiting, hormonal imbalances that may cause precocious puberty, or secondary parkinsonism.

Answer 47

You had pain, but also decrease in sensation. Think of dermatome map and that points you to C8. What about ulnar nerve. The left neck pain lets you know it is up near the vertebral column. The motor, weakness of intrinsic muscles of hand. Most likely is herniation between C7 and T1 impinging on C8.

Answer 48

So very different from a spinal nerve impingement, this is a total transection where everything is lost. Interruption of these long pathways is the reason spinal cord injuries leads to major loss in function BELOW THE LEVEL OF THE LESION. Descending efferents can't reach targets, Ascending sensory output can't reach the brain.

Answer 49

The foot is dropped (refer the picture) - problem with anterior tibia, some wasting of muscles, \\Symptoms Weakness in the R leg mostly, but also the L leg 2. Atrophy of the leg muscles 3. Time course: Progressive, and she had had a similar illness as a baby 4. Localization: broadly affects limbs (mainly lower) Cranial nerve testing: normal • Observation: Lower limb wasting. No upper limb wasting. • Strength test: Lower limbs had global weakness bilaterally—more in the right. • Reflexes: No reflexes in the lower limbs. • Sensory examination: Normal • MRI of the brain and whole spine normal, with mild scoliosis and minimal degenerative disease. • EMG (electromygraphy) studies showed partial denervation of leg muscles. Lower motor neuron syndrome 1. Weakness or paralysis 2. Atrophy 3. Hyporeflexia or areflexia 4. Decreased tone (resistance to passive movement) “flaccid paresis/paralysis” 5. Fibrillations, positive sharp waves or fasciculations, measured by EMG Symptoms will be in the muscles that are innervated by the motor neurons! This patient has post-polio syndrome. She has a history of polio. She also has a broad area of lower motor neurons. She also had a period of years which she was neurologically stable _usually 15 years, followed by progressive weakness in the same muscles originally affected.

Answer 50

Epidural hematoma - period of lucidity but things got really bad when the herniation happened

Answer 51

Vit B deficiency

Answer 52

Guillain Barre syndrome

Answer 53

Vincristine- common chemotherapy drug affecting long axons.

Answer 54

So you're thinking corticobulbar and corticospinal. But is not including the legs. So the lesion is in the primary motor cortex where the arm and face are.

Answer 55

Debbie is a 16-year-old girl who plays the piano and violin and has an active social life. Over the last four years, she has complained on-and-off to her parents that her arms and shoulder hurt and sometimes feel numb. At first, at about age 12, it was in her right shoulder (lateral aspect), but then moved to both sides. Her parents were concerned and recommended that she take breaks from her music (mainly the violin) for several weeks to relieve her symptoms. Recently, however, it has gotten worse, and her pediatrician referred her to a pediatric neurologist because of progressive arm and shoulder pain and numbness. When she arrived at the neurologist, she said that her major problem was that she had pain in both shoulders and lateral arms, and both hands felt “numb.” She did not have any gait problems, bladder incontinence, or other symptoms. The neurological exam was notable for decreased pinprick sensation on the lateral aspect of both arms and forearms, and in a cape distribution in her shoulder areas and superior-anterior chest area. The remainder of the exam was normal. What dermatome levels are affected, what two things are abnormal, what would the lesion likely be?

Answer 56

-acute inflammatory demyelination polyneuropathy (another name) - mostly rapidly progressing and potentially fatal form of neuropathy - most of the time, GB begins 1-3 weeks after infection or vaccination, ex: campylobacter jejuni, herpesvirus. -Infection causes an autoimmune/inflammatory attack on peripheral myelin. This time, MOSTLY MOTOR> ascending Symmetrical paralysis May begin with paresthesias in toes and fingers with aching in thighs and back. Ascending paralysis that can (if severe) affect breathing and require respiratory support. Diagnosis: Nerve conduction velocity is decreased -Albuminocytologic dissociation - increased protein in CSF with normal cell count

Answer 57

``` Multiple sclerosis: Multiple sclerosis (MS) is a potentially disabling disease of the brain and spinal cord (central nervous system). ``` In MS, the immune system attacks the protective sheath (myelin) that covers nerve fibers and causes communication problems between your brain and the rest of your body. Eventually, the disease can cause the nerves themselves to deteriorate or become permanently damaged. Signs and symptoms of MS vary widely and depend on the amount of nerve damage and which nerves are affected. Some people with severe MS may lose the ability to walk independently or at all, while others may experience long periods of remission without any new symptoms. There's no cure for multiple sclerosis. However, treatments can help speed recovery from attacks, modify the course of the disease and manage symptoms. This damage disrupts the ability of parts of the nervous system to communicate, resulting in a range of signs and symptoms, including physical, mental, and sometimes psychiatric problems.[5][8][9] Specific symptoms can include double vision, blindness in one eye, muscle weakness, trouble with sensation, or trouble with coordination.[1] MS takes several forms, with new symptoms either occurring in isolated attacks (relapsing forms) or building up over time (progressive forms).[10] Between attacks, symptoms may disappear completely; however, permanent neurological problems often remain, especially as the disease advances.[10]

Answer 58

Cushing’s triad: 1. hypertension, 2. bradycardia, 3. irregular respirations (brainstem) Caused by increased intracranial pressure

Answer 59

A group of diseases caused by degeneration of the anterior horns. These are progressive and begin in infancy. Due to abnormalities in chromosome 5 Motor neurons are affected in the spinal cord and cranial nerve motor nuclei _________________________________ Most common (and severe) type of spinal muscle atrophy is SMA I Werdnig-Hoffmann disease “acute infantile spinal muscle atrophy” __________ _________ autosomal-recessive inheritance pattern “floppy-baby” median age of death is 6-7 months. affects 1/10,000 lives births Symptoms: Weakness and muscle wasting in -limbs -respiratory -bulbar muscles: sucking, swallowing, breathing Pathological changes that occur with sustained lower motor neuron disease: e.g., polio, peripheral neuropathies.

Answer 60

Results in: oculomotor paresis ipsilateral, dilated pupil), contralateral hemiparesis:  Contralateral hemiparesis occurs with compression of the ipsilateral cerebral peduncle of the midbrain -  Since the corticospinal tracts decussate below the midbrain, the hemiparesis is contrateral  In addition to pupillary dilatation, a second key feature of uncal herniation is a decreasing level of consciousness (LOC) due to distortion of the ascending arousal systems as they pass through the midbrain]  A dilated pupil from in the absence of a LOC is not due to uncal herniation

Answer 61

Epidural hematoma: From trauma to the skull: usually from middle meningeal artery. • May also be from sinuses (~15%). •“Lens shaped” structure on MRI • Often has period of lucidity before severe symptoms (from a brain herniation). Subdural Hematoma: Horizontal (axial) MRI showing crescent-shaped subdural hematoma due to tearing of bridging veins, which often occurs during rapid accelerations. Symptoms may progress over longer periods. -common in elderly Subarachnoid hemorrhage: bleeding into the subarachnoid space usually secondary to head trauma. • Usually traumatic -["Non-traumatic” from bleeding from an A-V malformation or ruptured aneurysm. ``` A burst aneurysm is responsible for 80% of non-traumatic subarachnoid hemorrhages. • Aneurysms form when the vessel wall is weakened, and can burst under conditions of increased pressure. • Most aneurysms occur in the “anterior circulation” supplied by the internal carotid artery. ``` The classic presentation is sudden-onset, severe headache (from blood irritating meninges) "worst headache of my life" Subarachnoid is diagnosed by bloody CSF

Answer 62

Hydrocephalus: Condition of excess CSF 1- excess production (choroid plexus tumors) 2- obstructed flow anywhere in ventricles or subarachnoid space (tumors, malformations, hemorrhage) 3- decreased reabsorption via arachnoid granulations. “Communicating hydrocephalus”: lateral ventricles communicate with subarachnoid space. “non-communicating hydrocephalus”: flow obstructed within the ventricular system. ``` Symptoms: Children and Adults: -Headache (especially in the morning)* Decreased cognitive function Neck pain Vomiting (especially in the morning)* Blurred vision (papilledema) Drowsiness Failure of upward gaze ``` *CSF is less reabsorbed when lying down.

Answer 63

-the most common Congenital hindbrain anatomic anomalies associated with the downward displacement of the cerebellum, brainstem or craniocervical junction. -produce hydrocephalus Cerebellar tonsils below the foramen magnum 2. Syringomyelia (Chiari is most common cause) Syringomyelia is the development of a fluid-filled cyst (syrinx) within your spinal cord. Over time, the cyst may enlarge, damaging your spinal cord and causing pain, weakness and stiffness, among other symptoms. 3. Compression of brainstem ``` Most common symptoms are • Headache (increased intracranial pressure), • Ataxia (cerebellar dysfunction), and • Impaired movement (brainstem compression) ```

Answer 64

Less common Significant herniation through foramen magnum cerebellar tonsils and vermis lower brainstem • Causes aqueductal stenosis and Hydrocephalus. • Usually with meningomyocele - Meningomyelocele is a type of spina bifida. Spina bifida is a birth defect in which the spinal canal and the backbone don’t close before the baby is born. This type of birth defect is also called a neural tube defect. The spinal cord and the meninges (the tissue that covers the spinal cord) may actually protrude through the child’s back. In some cases that skin covers the spinal cord and meninges, it may also stick through the skin. - syrinx in base of spinal cord

Answer 65

-occurs in the elderly Classic triad of symptoms 1. Dementia (of varying degrees) 2. Urinary incontinence: May present as urgency, frequency, or a diminished awareness of the need to urinate 3. Gait disturbance: Usually the first symptom; magnetic gait. : ***NOTE NO HEADACHE May be related to impaired reabsoprtion from meningitis or subarachnoid hemorrhage

Answer 66

.damage to a spinal nerve The most common pathology to spinal nerves are herniated discs. -Osteophytes can also cause radiculopathy -spinal stenosis - hypertrophy of ligamentum flavum -Foramen stenosis-hypertrophy of facet Typical Symptoms related to radiculopathy 1. Burning, tingling pain that radiates from the back along dermatome a. “lancinating” or stabbing pain b. Location, location, location 2. Numbness (anesthesia, analgesia) a. possible, but there is overlap in dermatomes. b. analgesia, tested with a pinprick may be more sensitive 3. Worsening of symptoms with coughing, sneezing, straining. Flexing the head in the case of cervical radiculopathy. 4. Muscle weakness ***5. T1 radiculopathy can cause a Horner’s syndrome, because it interrupts the sympathetic pathway to the eye. a. constricted pupil (miosis) b. anhidrosis (decreased sweating) of the skin of the face c. ptosis (drooping) of the eyelid

Answer 67

T1 radiculopathy can cause a Horner’s syndrome, because it interrupts the sympathetic pathway to the eye. a. constricted pupil (miosis) b. anhidrosis (decreased sweating) of the skin of the face c. ptosis (drooping) of the eyelid

Answer 68

Chiari 1: Findings typically asymptomatic in children abnormally shaped cerebellar tonsils are downwardly displaced through the foramen magnum Associated condition: syringomyelia ``` Chiari 2: Findings typically symptomatic cerebellar vermis and tonsil are downwardly displaced through the foramen magnum Associated condition spinal meningomyelocele ```

Answer 69

In individuals with the rare Dandy-Walker syndrome, there is congenital malformation of the cerebellum, which may result from cystic enlargement of the 4th ventricle and leads to developmental delays, defective muscle tone, poor coordination and balance (ataxia), and sometimes hydrocephalus.

Answer 70

Weakness: Yes in both (only similarity) Atrophy: Only in LMN, mild from disuse in UMN. Fasciculations: Only in LMN Reflexes: Increased in UMN, decreased in LMN Tone: Increased in UMN, decreased in LMN

Answer 71

Corticobulbar tract lesion: Exceptions to compensation: 1- lower nucleus of VII. These go to the lower face. 2- mostly contralateral to CN XII (motor neurons to the tongue.) Lesions to one corticobulbar tract produce the following deficit: 1- Paralysis to contralateral lower face. 2- Some paralysis to the opposite tongue, and difficulty swallowing (dysphagia). Bell's palsy: -Right Cranial nerve VII lesion (Bell’s palsy) causes lower motor neuron paralysis of ½ the face. Both upper and lower face affected on right or left -corticobulbar is only contralateral lower face

Answer 72

Decorticate - lesion ABOVE midbrain - upper limb: flexed - elbow, finger - lower limb: extended: knee DEcErEbratE - lesion BELOW midbrain All limbs Extend

Answer 73

- hyperreflexia - thought to be because the muscle becomes super sensitive without period stimulation from UMN so you get a really strong sensory response at the level - Clonus - rhythmic contractions of antagonist muscles- lets say you flex at the ankle joint, pt with UMN injury will be sent into involuntary movements of up and down. - Hypertonia - when a doctor moves the leg around, there is more resistance, instead of relaxed like LMN - Extensor Plantar response aka Babinski sign : if you take a hard object, scrape up along bottom foot, normal plantar response is flexor.

Answer 74

1. Wallerian degeneration: axonal damage leads to "dying forward". - distal axon degeneration - Chromatolysis of cell body, nucleolus expands and moves to cell membrane, Nissil substance disintegrates - Recruit macrophages distal to lesion 2. Axonal degeneration: Conditions that affect the health of neurons such as metabolic disease leads to "dying back" of axons. Loss of myelin CAN accompany this process. **LONGER axons are affected FIRST, resulting in distal extremities being affected first - (diabetic neuropathy) 3. Segmental demyelination: occurs when sheaths are damaged by trauma or disease. Myelin may be affected secondarily to axonal death - Symptoms are detected by nerve conduction tests - conduction block or slow - Myelin and conduction can return in days to weeks *Only 1 and 2 result in muscle atrophy

Answer 75

When symptoms follow a nerve root pattern, (dermatome OR myotome) it is referred to as a radiculopathy. Often caused by compression of nerve roots from protruding discs. ex. A herpes zoster infection arising in the sensory neurons of the dorsal root ganglion of T1 spinal nerves, may produce just sensory symptoms (pain) at the T1 dermatome (usually unilateral). When symptoms follow a peripheral nerve it is referred to as a mononeuropathy, often caused by injuries - ex carpal tunnel , sensory, motor and autonomic components distal to wrist Mononeuropathy multiplex: Mononeuritis multiplex is a painful, asymmetrical, asynchronous sensory and motor peripheral neuropathy involving isolated damage to at least 2 separate nerve areas. Multiple nerves in random areas of the body can be affected. As the condition worsens, it becomes less multifocal and more symmetrical. Mononeuropathy multiplex syndromes can be distributed bilaterally, distally, and proximally throughout the body Plexopathy: unlike mononeuropathy, this is lesion of a network of nerves. The region of nerves it affects are at the brachial or lumbosacral plexus. Symptoms include pain, loss of motor control, and sensory deficits. Polyneuropathy: is damage or disease affecting multiple peripheral nerves (peripheral neuropathy) in roughly the same areas on both sides of the body, featuring weakness, numbness, and burning pain. -show a distal and symmetric sensorimotor (maybe autonomic) distribution. Sometimes called glove and stocking pattern. Most common causes are diabetes, alcohol, hypothyroidism, vit B12 deficiency.

Answer 76

-Length dependent diabetic polyneuropathy accounts for >80% of patients with diabetic neuropathy. Symptoms begin in the feet, then move to more proximal legs and distal upper limbs. (most nutritional, metabolic and toxic diseases produce this pattern of distal neuropathy) Patho: Axonal dying back, degeneration and demyelination occurs - includes effects related to ischemia, oxidative stress and inflammatory processes - SENSORY (as with all distal neuropathies) are MORE affected than motor. The sensory deficits involve most small UNmyelinated and myelinated fibers ("small fiber polyneuropathy") Symptoms: paresthesias (tingling or prickling sensation), dysesthesias (impairment of sensitivity especially to touch). Can lead to trophic changes like calluses and plantar ulcers. Histo: decreased number of myelinated and unmyelinated axons -thickening of walls of blood vessels

Answer 77

Symptoms: distal limbs - beginning more commonly in the upper limb instead of the feet like diabetics. * *Loss of vibration sense is most common feature. - also pain numbness and tingling in hands or feet, sensory loss and motor weakness Subacute combined degeneration: May primarily or secondarily affect lateral and dorsal columns of the spinal cord. Therefore ataxia and spasticity can occur together with symptoms of peripheral neuropathy. Without B12 myelin production is abnormal Diagnosis: *NCV will decrease

Answer 78

Group of several hereditary diseases that either affect myelin (CMT1) or axons (CMT2) directly. CMT1 is most common, produces a motor sensory neuropathy. - primarily affects distal muscle, particularly the peroneal nerve - because of demyelination, small fiber types carrying pain and temperature are not affected - frequently occurs with pes cavus and hammertoes *true for all CMT -typical onset is late childhood, identifiable by slowly progressive nature and reduced conduction velocity in all nerves

Answer 79

Lesion of parietal lobe or primary sensory cortex: -Contralateral numb tingling or pain Lesion of thalamus: -Contralateral burning pain = Dejerine-Roussy (Thalamic/Central) Syndrome Lesion of dorsal column medial lemniscus (DCMLS): - Tingling, numb sensation - Tight band-like sensation around the trunk or limbs - Feeling of having gauze on fingers - Electricity sensation down back and extremities upon neck flexion = Lhermitte ’s sign (if lesion is cervical) Lesions of anterolateral (spinothalamic STT) pathways Sharp, burning or searing pain Lesion of nerve roots -Radicular pain with numbness and tingling in dermatomal distribution = radiculopathy

Answer 80

Loss of sensory, motor, reflex and autonomic function below lesion. Acute onset causes spinal shock syndrome Causes: 1. fracture/dislocation trauma by MVA, dive in pool, fall off horse, etc, usually in the cervical region, or bullet/knife wound 2. demyelinating disease- MS, post-infectious transverse myelitis 3. compression by tumor or inflammatory mass Rate: Helps identify etiology; acute versus slowly evolving An acute syndrome elicits spinal shock, which can last several weeks, and consists of loss of all sensation, flaccid paralysis, loss of reflexes, and no bowel/bladder function. ``` Chronically, there will emerge -hyper-active reflexes (clonus) - increased tone -Babinski sign which together we term spasticity. Over time there will be flexor spasms, set off by simple cutaneous stimulation, and later automatic bladder emptying that occurs after it fills. If the lesion is sacral, the bladder will distend and overflow causing emptying with chronic infection. ```

Answer 81

Ipsilateral to lesion: weakness, increased tone, and hyperreflexia, paresthesia, proprioceptive loss, root pain. Contralateral to lesion: loss of pain and thermal sense *Dissociated sensory loss Spinal hemisection- example, C4 level Ipsilateral corticospinal tract- UMN syndrome - weakness of arm and leg mild atrophy -hyper-reflexia (clonus of ankle), - Babinski sign loss of abdominal and anal wink Ipsilateral posterior (dorsal) column- position and vibration Contralateral loss of pain (pin), temperature Autonomics- Horner's syndrome (miosis, ptosis, anhydrosis) C4 level exhibits complete loss of motor and sensory root functions- including sensation in dermatomal pattern if 2 roots, reduced C4 muscle (LMN) innervation (function).

Answer 82

Syringomyelia/Central Cord Syndrome Cavitation near the central canal of the spinal cord Causes- developmental, vascular (AVM), trauma, infections, astrocytic tumor, congenital malformations. Most commonly occur from C3 to T4. Example: C4-C8 1. Initially experience a cape (shawl) distribution of lost spinothalamic fibers crossing at the ventral commissure, giving rise to reduced pin and temperature over lateral arms, forearms and fingers. 2. As it expands, will include shoulders, back and anterior thorax, but preservation of dorsal columns. 3. Further expansion into the ventral horn compromises ventral motoneurons, yielding LMN flaccid weakness of shoulders, arms, forearms and hands. 4. Finally, expansion into lateral funiculus interrupts descending corticospinal tracts, with UMN syndrome. Thus early on there is a segmental loss of sensory and motor pathways, whereas later, all functions below the lesion are effected except those most peripherally localized, giving rise to *sacral sparing.

Answer 83

- Atrophic weakness of hands/forearms; - spasticity of legs; - generalized hyperreflexia; - a mixed UMN and LMN disorder progressive spread both rostrally and caudally until fatal - LMN signs with loss of strength, reduced tone, atrophy and loss of reflexes, all due to muscle denervation. Some of these signs are apparently reversed by appearance of hyper-reflexia from loss of UMN innervation. Most common initial symptoms: stiffness/weakness and muscle wasting of hands/fingers, hand cramping, and later twitching of forearms (fasciculations) Only upper and lower motor neurons affected, no sensory involvement

Answer 84

Oligodendroglioma WHO grade 2 or 3. Usually cerebral hemispheres and often hemorrhagic.

Answer 85

*bitemporal hemianopsia Hormone overproduction 1. Prolactin: amenorrhea, galactorrhea: milky nipple discharge unrelated to the normal milk production of breast-feeding. 2. Growth hormone - acromegaly 3. ACTH- Cushing's Disease

Answer 86

Craniopharyngioma - in very young kids think this not adenoma.

Answer 87

Neurofibromatosis type 2 -additionally meningioma 50% of cases and ependymoma Encodes for Merlin which links proproliferation signals with underlying actin cytoskeleton.

Answer 88

Schwannoma

Answer 89

meningeoma

Answer 90

Hemangioblastoma - Von Hippel Lindau mutation leading to constitutive activation of HIF, leading to overproduction of angiogenic growth factors .

Answer 91

medulloblastoma, | normal neurons are synaptophysin negative.

Answer 92

- palisading necrosis - butterfly lesion - microvascular proliferation - EGFR - tenzolomide - MGMT methylation - gadolinium, ring enhancing lesion.

Answer 93

1. Schwannoma 100% 2. Meningioma 50% 3. Ependymoma

Answer 94

Multiple sclerosis: 1. Dorsal column, 2. CST 3. Cerebellar tracts (ataxia, dysmetria: inability to judge distance or scale of movements, nystagmus: rapid involuntary movements of eyes, dysarthria: slurred speech) Anterior spinal artery: 1. no dorsal column 2. CST (anterior and lateral) 3. Cerebellar tracts ``` B12 deficiency: 1. dorsal columns MOST affected 2. CST 3. Cerebellar tracts 4. Peripheral nerve (UMN > LMN, in this order) ``` ALS: motor only! (compare to B12) 1. Peripheral nerves 2. CST 3. no sensory involvement ``` Central cord: (cervical usually) Early: 1. spinothalamic (shawl) Expanded: 1. Spinothalamic (shawl) 2. Ventral horns (LMN) 3. CST (with sacral sparing) 4. Can include dorsal column ``` Extramedullary Compression: 1. Dorsal root (reduced triceps reflex) 2. Dorsal column compression 3. CST 4. Ventral horn compression

Answer 95

Neural tube formation (neurulation) occurs with induction of ectoderm by secretion of factors from the underlying notochord (a midline rod of mesoderm) so that developing neuroectoderm cells organize in the midline as a thickening called the neural plate. (Recall that notochord eventually forms the nucleus pulposus of intervertebral discs in the adult.) The neural tube wall is made up of neuroepithelial cells that proliferate and differentiate to form the neurons and neuroglia of the CNS. The main signal that triggers the development of the ventral part of the neural tube is the production of sonic hedgehog (SHH) by the notochord and subsequent differentiate of ventral cells of the neural tube. Signals responsible for development of the dorsal part of the neural tube are produced by surface ectoderm (developing skin epidermis) include many of the TGF-beta family. The sulcus limitans separates the developing neural tube into dorsal and ventral halves throughout the developing brainstem and spinal cord. Proliferation of neuroectoderm cells in the neural plate results in “buckling”/folding of tissue to form a depression called the neural groove with raised bilateral neural folds. With further proliferation (and more buckling of a deepening neural groove), the edges of the neural folds approximate and fuse in the dorsal midline to form the neural tube, which detaches from the epidermis-forming surface ectoderm. The caudal end of the neural plate and tube, which is narrower than the cranial end, will become the spinal cord, whereas the wider, cranial end will become the brain. - Fusion to form the neural tube begins in the cervical region and occurs as a bi-directional “zipper” that proceeds cranially and caudally. The open (unfused) ends of the neural tube are called neuropores. The final step of primary neurulation is neuropore closure, which occurs by the end of week 4. Note that the cranial (anterior) neuropore closes by day 25 and the caudal (posterior) neuropore closes by day 28. The brain and most of the spinal cord (up to L1-L2) forms from the neural plate-derived neural tube through primary neurulation. The remaining caudal component of the spinal cord forms from local tissues through secondary neurulation. *

Answer 96

The rhombencephalon divides into the metencephalon (forms pons and cerebellum; associated CNs V, VI, VII, VIII) and myelencephalon (forms medulla; associated with CN IX, X, XI, XII). ______________________________________ The pontine flexure does not persist as a bend in the future brainstem. The alar and basal plates in the rhombencephalon wall near the developing pontine flexure spread apart along the rhombencephalon’s neural canal/lumen, known as the 4th ventricle. Thus, the basal plates and alar plates end up lying along the floor of the 4th ventricle and the roof of the 4th ventricle is a thin membrane. In contrast to the dorsal sensory alar plates and the ventral motor basal plates of the spinal cord, this region of the rhombencephalon (future pons and medulla) forms sensory nuclei that are located lateral (rather than dorsal/posterior) to motor nuclei.

Answer 97

.The mesencephalon is the midbrain (associated with CNs III, IV). The mesencephalon is cranial to the spinal cord and rhombencephalon and forms the midbrain component of the brainstem. The mesencephalon contains basal and alar plates. The nuclei of the basal plates are made of two groups of efferent/motor neurons in the mesencephalon whose axons course in cranial nerves III, IV to supply almost all extrinsic skeletal muscles of the eye (for eyeball movement). Neuron cell bodies that make up the Edinger-Westphal nucleus in the midbrain send axons fibers through CN III to the innervate pupillary sphincter/constrictor muscle and ciliary muscle The dorsally-located alar components of the midbrain are colliculi that serve as sensory synaptic relays for visual and auditory information. The colliculi are formed by neuroblasts migrating to the overlying marginal zone. The cerebral aqueduct (of Sylvius) forms from the lumen of the mesencephalon.

Answer 98

Prosencephalon - divides into the telencephalon (forms cerebral hemispheres; associated with CN1) and diencephalon (forms optic cup, pineal gland, thalamus, hypothalamus posterior pituitary; associated with CN II) Diencephalon - Optic vesicles evaginate from the diencephalon and are associated with CN II/optic nerve-tract-chiasma. Optic vesicles induce the overlying surface ectodermal lens placode to form the lens. - The diencephalon consists of a roof plate, two alar plates, no (or very little) floor or basal plates. The most caudal part of the roof plate develops into the pineal body/epiphysis for light-darkness behavioral rhythms. - The alar plates form the lateral walls of the diencephalon. Neuroblast in the alar plates of the diencephalon walls proliferate to form `the hypothalamus and thalamus. The thalamus proliferates and bulges into the lumen of the diencephalon. The hypothalamus differentiates into a number of nuclear areas that regulate visceral functions, including sleep, digestion, body temperature, emotional behavior. - The hypophysis/pituitary gland, develops form two completely different parts: The posterior pituitary/neurophypophysis forms from the infundibulum, a ventral extension of the diencephalon. • The anterior pituitary forms from the adenohypophyseal placode that buds off the primitive oral cavity immediately anterior to oropharyngeal membrane as Rathke's pouch. The developing anterior pituitary grows towards the infundibulum and loses its connection with the oral cavity _____________________________________ Telencephalon - Development of the brain is dominated by dramatic growth of bilateral outpocketings/projections/ evaginations/swellings of the telencephalon to form cerebral hemispheres. The cerebral hemispheres grow to cover other brain regions (diencephalon, midbrain, hindbrain) and meet/flatten medially in the midline. Growth of the cerebral cortex (outer gray matter) forms lobes (frontal, parietal, temporal, occipital) and increases surface area through foldings that form sulci, fissures, gyri. - In the cerebrum, the lamina terminalis is an early bridge between two cerebral hemispheres where tracts (fiber bundles) interconnect the two cerebral hemispheres. Continued tract formation for cross communication between the cerebral hemispheres forms commissures. The anterior commissure and corpus callosum (two prominent commissures in the adult brain) maintain attachments to the lamina terminalis. - The basal part of the telencephalon, adjacent to the diencephalon, thickens to form the gray masses called the basal nuclei. The hippocampus and cranial nerve I (olfactory bulb and tract/nerve) are also derived from the telencephalon. - The neural canal/lumen of the telencephalon become the cavities of the hemispheres, the lateral ventricles, which communicate with the lumen diencephalon through interventricular foramina of Monro, - By birth, the cerebral cortex in the outer gray matter is made up of six layers that form as multiple waves of neuroblast migration from the ventricular layer of proliferating neuroepithelial cells. Layer formation occurs as each neuroblast wave migrates superficially to the subpial position and differentiates into fully mature neurons. When the next wave of neuroblasts arrives, neuroblasts migrate through the earlier formed layers of cells until they reach the subpial position. Thus, the early formed neuroblasts are deep position in the cortex (layer VI), whereas those formed later obtain a more superficial position (layer I).

Answer 99

Neural Tube Defects (NTDs) are severe congenital defects (birth defects) of the CNS that usually result from failure of neuropores to close during week 4. If neuropores remain open, abnormalities in skin, skull, vertebrae, meninges, muscles, neural tissues may be seen and there is a connection between the amniotic cavity and vertebral canal. - In 1/5000 live births, defective closure of the cranial neuropore results in anencephaly and the failure to form the cranial vault around cerebral hemispheres. Anencephaly is lethal (usually) because the malformed brain is exposed to amniotic fluid, which leads to its degeneration and necrosis. Because anencephalic fetuses lack swallowing reflex, the last trimester of pregnancy is characterized by polyhydramnios (excess amniotic fluid in sac) and is a risk factor is maternal type 1 diabetes. - Defective closure of the caudal neuropore results in spina bifida, in which there is at least a defective fusion of vertebral arches (commonly at L4-S1). - Defective closure of the entire neural tube CNS is seen as an open furrow on the dorsal surface of the head and body and results in a fatal deformity called craniorachischisis (“cleft skull and spine”). Spina bifida occulta does not cause disability and is usually an incidental finding during back x-ray. It is present in 10% of otherwise normal people as a defect in the fusion of vertebral arches (usually S1-S2) without herniation of underlying neural tissue and is covered by skin which may or may not grow an abnormal tuft of hair in the region over the defect. -Spina bifida cystica is a severe defect in the fusion of vertebral arches in which neural tissue and/or meninges protrude through the defect in the vertebral arches and skin. It is a severe defect in the fusion of vertebral arches with involvement of underlying neural tissue that appears as a cyst-like sac and results in neurological deficits (but not usually associated with intellectual disability). Spina bifida cystica includes the following types: - spina bifida cystica with meningocele in which only fluid-filled meninges protrude through defect - spina bifida cystica with meningomyelocele in which fluid-filled meninges and neural tissue protrude through defect; Hydrocephaly often develops in children with severe NTDs. For example, in some infants with spina bifida with meningomylocele, there is also Arnold-Chiari malformation (type II) in which the spinal cord is abnormally tethered to the growing and lengthening vertebral column that pulls the cerebellum inferiorly to herniate into the foramen magnum and obstructs CSF flow. There may also be paralysis and sensory loss at and below the level of the lesion. (Hydrocephalus can be treated by inserting a ventriculoperitoneal shunt, which allows drainage of CSF from one of cerebral ventricles into peritoneal cavity.) - spina bifida cystica with rachischisis/myeloschisis in which neural folds do not elevate and fuse Defects in skull formation, frequently in the occipital region, can also result in - meningoceles in which only meninges bulge through a small opening in the skull - meningoencephaloceles in which meninges and brain bulges through a large opening in the skull - meningohydroencephaloceles in which meninges, brain tissue, and ventricles bulge through a larger opening in the skull

Answer 100

Detecting AFP levels: Alpha-fetoprotein (AFP) is an abundant plasma protein of fetal serum that is produced by fetal yolk sac and liver. AFP passes through fetal urine into amniotic fluid and reaches maternal blood. AFP can also directly pass into amniotic fluid if there is a NTD (or abdominal wall defect) and result in elevated AFP levels in amniotic fluid and maternal blood. Screening for severe NTDs that involve herniation of neural tissues is accomplished by measuring for elevated AFP levels in maternal blood at 15-20 weeks gestation. Acetylcholinesterase (AChE) is primarily active in the CNS and normal amniotic fluid does not contain AChE, unless contributed by the fetus as a result of an open NTD. Elevated AFP and acetylcholinesterase are indicators for fetal ultrasonography. The most common cause of elevated AFP levels is underestimation of gestational age/dating error. Prenatal ultrasound is used to confirm gestational age and for detection/diagnosis of NTDs or abdominal wall defects. Surgery can be performed in utero at ~22 weeks to repair the defect.

Answer 101

In embryogenesis, Rathke's pouch is an evagination at the roof of the developing mouth in front of the buccopharyngeal membrane. It gives rise to the anterior pituitary (adenohypophysis), a part of the endocrine system.

Answer 102

A ruptured berry aneurysm- sudden onset severe headache is a classic sign of subarachnoid hemorrhage. A rupture berry aneurysm is the most common cause of a nontraumatic subarachnoid hemorrhage. `

Answer 103

right C5 - the brachioradialis and biceps stretch reflexes are mediated by C5-C6 afferents and efferents so these would be weakened by a C5 lesion. The sensory pattern suggests a C5 lesion.

Answer 104

Chiari type 1malformation. Most common symptoms are a syrinx, headache, cerebellar dysfunciton and impaired movement from brain stem compression. Meningomyelocele which was not present in this case is associated with chiari malformation type 2.

Answer 105

The symptoms are upper motor neuron syndrome. So you should remember the course of the corticospinal tract. With symptoms on the right the affected tract would begin in the left motor cortex, descend through the internal capsule and cerebral crus, cross over in the pyramidal decussion. A: left internal capsule.

Answer 106

Verocay bodies, Schwannoma, NF2. NF1 would have more PNS presentation like cutaneous neurofibromas.

Answer 107

- nociceptors require higher temperatures to be activated - within the range of painful temperatures, thermoreceptors fire at a constant right - over a range of increasingly painful temperatures, nociceptors fire at an increasing rate

Answer 108

Bony osteophytes at C4-C5 causing left C5 radiculopathy. Left shoulder pain and decreased sensation, left deltoid weakness.

Answer 109

L5-S1 posterolateral disc herniation causing left S1 radiculopathy.

Answer 110

It will increase the duration of anesthetic action (useful if short or medium duration). Vasoconstriction that prolongs duration also means less local anesthetic is needed so risk of toxicity (seizure) is reduced.

Answer 111

naltrexone - has a much longer half life than naloxone.

Answer 112

Opioid abstinence syndrome aka withdrawal. Usually starting 6-10 hours after last dose. Rhinorrhea, lacrimation, piloerection, muscle jerks and yawning.

Answer 113

Guillain-Barre syndrome: acute onset of bilateral lower extremity weakness and sensory deficits. Stroke would not be bilateral.

Answer 114

A noncontrast head CT is the standard for evaluation of acute blood which would be hyperdense. Subtle areas of acute blood may not be seen on MRI. Cather angiography would be appropriate for evaluation of intracranial vasculature.

Answer 115

Syringomyelia - pain and temperature are affected without any other sensory or motor functions. Syringomyelia affects a dermatomal distribution so a long pathway is not involved. Although peripheral neuropathies like those due to diabetes, it can selectively affect pain and temperature, the pattern of sensory loss usually affects the distal limb rather than an entire dermatome.

Answer 116

Decreased blood B12 levels - can produce dorsal column lesions and can also affect the central nervous system. Diabetes does into affect CNS neurons. A subdural hematoma would not be likely to produce the vibration and proprioceptive losses.

Answer 117

In this case Mepivacaine was good. pKa 7.8, minimally lipophilic. The LOWER the pKa and lower the lipophilicity, the faster the onset of blockade. Benzocaine has a very low pKA but it is used only as topical anesthetic. Quick onset also think ester.

Answer 118

Like methadone it is used in opiate detoxification and could precipitate withdrawal. *the only partial agonist

Answer 119

Case is most likely herpes zoster. Reactivation of latent varicella-zoster virus in dorsal root ganglia results in a decrease in the threshold of activation for sensory neurons so there is spontaneous firing and persistent pain. The dermatomal region innervated by that DRG>

Answer 120

The thumb and forefinger are both innervated by C6 and the median nerve. One way to distinguish between the two is to determine whether the sensory loss is also in the C6 dermatome above the wrist. The tricpes reflex would not be helpful because it tests C7! and the C5 dermatome is not part of the differential because C5 does not innervate the palmar hand. Grip strenght could be decreased in all conditions and would not be useful.

Answer 121

Prosopagnosia and achromatopsia (commonly together). The damage confined to the ventral aspects of the occipital and temporal fields and is bilateral .These regions house the fusiform face area and bilateral damage leads to prosopagnosia. V4 primarily concerned with color processing also resides in this area and damage can lead to ahcromatopsia. Akinetopsia is usually associated with damage to V5 which is on the lateral surface of the brain.

Answer 122

Contralateral homonymous superior quadrantanopia and is produced by interruption of Meyer's loop passing anteriorly through the temporal lobe. This part of the optic radiation contains information from the contralateral upper portion of the visual field as seen by both eyes.

Answer 123

Inferior bitemporal quadrantanopsia.

Answer 124

right contralateral homonymous hemianopia.

Answer 125

A beta 2 agonist

Answer 126

Increases CSF pressure due to space occupying lesions (tumor and ruptured cerebral artery) can compress the central retinal vein in the optic nerve reducing venous return and causing papilledema. The central retinal artery is not affected due to its higher pressure and thicker wall.

Answer 127

Tropicamide: muscarinic antagonist to induce mydriasis Atropine: a muscarinic antagonist user to induce cycloplegia. (No accomodation) Phenylephrine: alpha agonist used to contract dilator muscle to induce mydriasis Timolol (beta blocker): decreases production of aqueous humor Brinzolamide (carbonic anhydrase inhibitor): decreases production of aqueous humor.

Answer 128

Age-related macular degeneration (AMD) Dry AMD is the non-neovascular form of AMD. It is characterized by drusen (yellow- white lesions in the outer retinal layers of the macula) or atrophy within the macula. Dry AMD may lead to wet (neovascular) AMD, which is associated with a choroidal neovascular membrane (CNVM). The CNVM is an abnormal growth of subretinal blood vessels, which grows in the macula or fovea and affects vision due to fluid leakage.

Answer 129

This patient is presenting with urgent ophthalmologic disease. She has classic symptoms of retinal detachment—flashing lights, visual field disruption, and floaters. Also, the majority of her vision is still intact. In her current state, she has a high likelihood of retaining good vision. None of the other treatments offered do anything for retinal detachment

Answer 130

Left plantarflexion weakness when asked to stand on toes

Answer 131

abnormal: before the LGN Normal: after the LGN, optic radiation, visual cortex, because axons reaching pretectum will leave before synapsing

Answer 132

Right temporal lobe tumor, compressing the right Meyer loop

Answer 133

Ciliary muscle: Contraction (M3) for near vision or relaxation (β2) for distant vision • Sphincter pupillae muscle: Contraction (M3) to decrease the diameter of the iris to reduce the amount of light entering the eye. • Dilator pupillae muscle: Contraction (alpha1) to increase the diameter of the pupil to allow more light to enter the eye. • Ciliary epithelium. ↑ production (β2) of aqueous humor- decrease (alpha2)

Answer 134

Beta blockers reduce production of aqueous humor to lower intraocular pressure. (beta receptors - ciliary body) Muscarinic agonists or cholinesterase inhibitors facilitate outflow to reduce IOP. (muscarinic receptors on ciliary body causes tension of trabecular meshwork to increase outflow of Canal of Schlemn)

Answer 135

1. Prostaglandin analogs - increase outflow 2. Beta blocker - decrease aqueous humor production 3. Carbonic anhydrase inhibitors: decrease aqueous humor production 4. Alpha2-agonists - do both, decrease aqueous humor production, increase outflow 5. Cholinergic agonist/ cholinesterase inhibitors: contract muscle fibers in ciliary body, increase in AH outflow 6. Osmotic agents, increase the osmotic agents leading to fluid going into blood.

Answer 136

1. tropicamide - duration of effect - 4 hours - this short duration is important for mydriasis on optic exam - (muscarinic activation cause contraction of pupillary constrictor muscle) 2. Scopolamine - 3-7 days - formulated as a patch for motion sickness, 3. Atropine - 7-10 days - target is the ciliary muscle because half life is too long, control accommodation. - effect is cycloplegia (blocking of accommodation important for the treatment of lazy eye amblyopia

Answer 137

Dry as a bone, blind as a bat, mad as a hatter, hot as hell, red as a beet, full as a flask. - decrease secretion and salivation because exocrine glands feature M3 muscarinic receptors - cycloplegia - ciliary muscle paralysis, can't focus on close objects - CNS excitation, restlessness, irritability - decreased ability to sweat - cutaneous vasodilation - urinary retention

Answer 138

Central Retinal Branch Occlusion. *if found in a young person - prompt inflammatory/hypercoaguability workup.

Answer 139

Uveitis: Redness • Pain • Photophobia - it hurts when the iris moves back and forth so they get photophobia. Treatments: Medications • Topical steroids - Durezol, prednisolone Mydriatic and Cycloplegic Agents • Atropine Sulfate 1% -the thought process is to keep the pupils dilated so as to keep the iris away from the lens capsule which inflammatory mediators can get the two stuck. Oral prednisone • Quick onset of action. Less risk of increase IOP and cataract. Systemic side effects. Immunomodulators • Humira, MTX, cyclosporin Regional depot triamcinolone (4mg) • Periocular • Intraocular

Answer 140

Glaucoma. Hypertension arises from the ciliary body and the Canal of Schlemn. Most people with glaucoma are managed by topical anti-hypertensive drops • Beta blockers - decrease production of aqueous humor. Put a valve connected to the anterior chamber which is equalized to a pressure. When pressure rises in the eye, the fluid will leave into the valve and take residence under the conjunctiva.

Answer 141

Touch the side of the cornea > afferent (opthalmic division of trigeminal) > spinal trigeminal nucleus >efferent limb - orbital part squinting, palpebral part (blinking) - facial nerve.

Answer 142

Papilledema is swelling of the optic disk (papilla) due to increased intracranial pressure (ICP) and is almost always bilateral. It may develop acutely (ruptured cerebral aneurysm) or over the course of several weeks or months (tumor). Patients may have symptoms of increased intracranial pressure, such as headache or nausea and vomiting. Papilledema requires an immediate search for the cause. Diagnosis is by ophthalmoscopy with further tests, usually brain imaging and sometimes subsequent lumbar puncture, to determine cause. Treatment is directed at the underlying condition.

Answer 143

Monocular inferior scotoma Right nasal hemianopia. Contralateral homonymous superior quadrantanopsia. Contralateral homonymous inferior quadrantanopsia

Answer 144

They would both be contralateral homonymous hemianopia but the one in the primary visual cortex would have macular sparing. Because macular representation is very large in primary visual cortex Also can receive blood supply from PCA and MCA

Answer 145

Infarct of posterior cerebral artery branches supplying lingual gyri causing lesion to right occipital lobe and preserving the right occipital pole.

Answer 146

``` Air: -1000 Fat: -100 Water: 0 Brain: 30-40 Acute Blood : 60-100 Calcification: 1000 ``` so anything brighter than brain is hyperdense (bone), anything darker is hypodense (fluid or fat)

Answer 147

Allows assessment of white matter tracts based on water diffusion characteristics along these tracts of axons ``` • Diffusion sequence used to form 3D image • Evaluation of neurodegenerative disease, epilepsy, traumatic brain injury, multiple sclerosis ``` • Role in preoperative evaluation – brain tumors

Answer 148

``` Functional MRI (fMRI) • Assess brain metabolic activity (indirect measure of neuronal discharge) and therefore specific areas of function ``` • Uses BOLD (blood oxygen level dependent) imaging. • Patient performs a repetitive task, i.e finger tapping • When brain is activated by a task, increase of blood flow leads to signal • Used to localize region of sensory function, motor function, and language • Role in preoperative evaluation

Answer 149

[Amyloidosis] Abnormal aggregation of proteins (or their fragments) into β-pleated linear sheets > insoluble fibrils > cellular damage and apoptosis. Amyloid deposits visualized by Congo red stain polarized light (apple green birefringence) and H&E stain (shows deposits in glomerular mesangial areas [white arrows], tubular basement membranes [black arrows]). AL (primary subtype) Due to deposition of proteins from Ig Light chains. Can occur as a plasma cell disorder or associated with multiple myeloma. Often affects multiple organ systems, including renal (nephrotic syndrome), cardiac (restrictive cardiomyopathy, arrhythmia), hematologic (easy bruising, splenomegaly), GI (hepatomegaly), and neurologic (neuropathy).

Answer 150

Seen with chronic inlammatory conditions such as rheumatoid arthritis, IBD, spondyloarthropathy, familial Mediterranean fever, protracted infection. Fibrils composed of serum Amyloid A. Often multisystem like AL amyloidosis.

Answer 151

Dialysis related: Fibrils composed of β2-microglobulin in patients with ESRD and/or on long-term dialysis. May present as carpal tunnel syndrome. Heritable: Heterogeneous group of disorders, including familial amyloid polyneuropathies due to transthyretin gene mutation. ``` Age related (senile systemic): Due to deposition of normal (wild-type) transthyretin (TTR) predominantly in cardiac ventricles. Slower progression of cardiac dysfunction relative to AL amyloidosis. ```

Answer 152

Amyloid deposition localized to a single organ. Most important form is amyloidosis in Alzheimer disease due to deposition of β-amyloid protein cleaved from amyloid precursor protein (APP). Islet amyloid polypeptide (IAPP) is commonly seen in diabetes mellitus type 2 and is caused by deposition of amylin in pancreatic islets. Isolated atrial amyloidosis due to atrial natriuretic peptide is common in normal aging and can predispose to increased risk of atrial fibrillation. Amyloid deposition to ventricular endomyocardium in restrictive cardiomyopathy. Calcitonin deposition in tumor cells in medullary carcinoma of the thyroid.

Answer 153

``` Common causes of meningitis NEWBORN (0–6 MO) 1. Group B streptococci 2. E coli 3. Listeria ``` CHILDREN (6 MO–6 YR) 1. S pneumoniae 2. N meningitidis 3. H influenzae type B 4. Enteroviruses 6-60 yr 1. S pneumoniae 2. N meningitidis #1 in teens 3. Enterovirus 4. HSV-2 60+ years 1. S pneumoniae 2. Gram negative rods 3. Listeria Give ceftriaxone and vancomycin empirically (add ampicillin if Listeria is suspected). Viral causes of meningitis: enteroviruses (especially coxsackievirus), HSV-2 (HSV-1 = encephalitis), HIV, West Nile virus (also causes encephalitis), VZV. In HIV: Cryptococcus spp. Note: Incidence of H inluenzae meningitis has reduced greatly due to conjugate H inluenzae vaccinations. Today, cases are usually seen in unimmunized children.

Answer 154

``` Bacterial: opening pressure: high cell type: PMNs (general term for WBCs) protein: high glucose: low ``` ``` Fungal/Tb: opening pressure: high cell type: lymphocyte protein: high glucose: low ``` ``` Viral: opening pressure: normal or high cell type: lymphocyte protein: normal/high glucose: normal ```